Underground storage systems and improved method of operating



April 16, 1957 G, R BENZ 2,788,637i

. UNDERGROUND STORAGE SYSTEMS AND IMPROVED METHOD OF OPERATING FiledyDeo. 4, 1952 3 Sheets-Sheet l AT @NED/S April 16, '1957 2,788,637

G. R. BENZ UNDERGROUND STORAGE SYSTEMS AND IMPROVED METHOD OF' OPERATINGFiled Deo. 4, 1952 3 Sheets-Sheet 2 g BY awPgIV;

AMM #JY April 16, 1957 Filed Dec. 4, 1952 G. R. BENZ 2,788,637UNDERGROUND STORAGE SYSTEMS AND IMPROVED METHOD OF' OPERATING 3Sheets-Sheet 3 A.United States Patent 0 r :UNDERGROUND STORAGE 'SYSTEMSA-N) `IMPROVED METHOD OF OPERATING George (R. Benz, Bartlesville,tOltla., assignor to Phillips Petroleum Company, a'corporation of`Delaware Application December 4, 1952Serial No. 324,074 9 Claims. (Cl.lf2-h1) This invention relates to an improved method of operating anunderground storage system. In one of its aspects this 4inventionrelates to a novel underground `storage system.

Constantly expanding production of liquefied petroleum .gas has createda definite problem in providing suit- .lable storage facilities for thismaterial. Due to the high vapor pressure of liquefied petroleum gas,particularly propane, the cost of storage in surface equipment, such assteel tanks, becomes excessive due to the massive construction requiredto withstand the vapor pressure of the stored material in `a safemanner. This problem becomes lextremely -acute where it is necessary tostore large quantities of such 'materials during the off season. .Inaddition to the expense involved, the use of steel tanks is limited byshortages in production.

In order to overcome these difficulties it has been proposed to "storeliquefied petroleum gas in porous waterbearing for-mations, inwater-leached Caverns, in salt formations, -or .in abandoned mines inimpermeable shale or llimestone formations. Further, undergroundconcrete storage tanks and buried sections of pipe have been used to alimited extent inthe storage of liquefied petroleum gas.

It iswell known that a liquefied gas can be forced AVfrom a chamber byintroducing compressed gas above the liquid. This method is widely usedin unloading LPG "ttik cars. Vapor is"withdrawn yfrom the storage tank,compressed and` pumped in'to the vapor space of the tank car. VThus'liquid i's forced `from the tank car into "the stofage tank through aconnecting line. A similar system "is Shown in U. S. `Patent '2,021,394in which LPG is 'forced from 'an underground tank toa Vcontainer on thesurface. i

liapplying` thiss'ystem to a large underground storage mine, however, alarge investment in compressors and prime movers" is required due to thelarge amount of vapor that must be compressed in order to start the flowof fluid` to Ythe surface, andthe operation is inefficient 'due to-large heat losses to the surrounding earth. It is to overcome these twodisadvantages that the present 'inventionis directed.

"il-.n accordance with this invention Van underground storage system forliquefied gases is provided which is capable of storing 'extremely largequantities of this maferial yat a very Asmall unit cost. Further., yinaccordance with this invention an improved method of operating'underground storage systems is provided whereby savings are effected inthe amount of vapor which `must be compressed in fthe removal ofliquefied gas from storage, and a lessening of Vheat loss to thesurrounding earth is effected. The, storage system of my invention isnot limited necessarily-to :the -storage of liquefied petroleum gas, butis .applicableto :the storage of liquefiable materials which do notatectand are not affected by the material of the cavern walls,A .as `forexample, ammonia and the like.

.lt-israrlobject:of` this .invention to provide underground storagefacilities of novel construction and arrangement,

2,788,637 Patented Apr. V16, 1.957

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said facilities providing storage at a minimum unitcost. lt is a furtherobject of this invention to provide an improved method of operating yanunderground storage system.

It is afurther object of this invention to provide a system in whichliquefiable material can be easily introduced into the storage systemand efficiently removed therefrom, and which provides safety from bombattacks, and increased protection against fire.

It is yet another object of this invention. to provide au undergroundstorage system capable of storing liquefied gases, such as propane,having a high vapor Apressure for an extended period with a minimum ofoperating dithculties.

Various other objects, advantages and features yof the invention willbecome apparent from the following detailed description taken inconjunction with the accompanying drawings, in which:

Figure l is a perspective View partly in section of one embodiment of myinvention employing two compressors;

Figure 2 is ya perspective view partly in section of another embodimentof my invention employing a single compressor;

Figure 3 is a perspective view partly in section of a third embodimentof my invention employing two smaller Caverns in conjunction with aplurality of large main storage Caverns.

Referring now in detail to Figure 1 of the drawing the large caverns aredivided by walls 10 and 11 into large chambers 12 and 13 and smallchambers 14 and 15. The lower regions of large chambers 12 and 13 areconnected with smaller chambers 14 and 15? by means of conduits 16 and.17 controllable from the surface by means of remotely controlled valves20 yand 21, respectively. The upper regions of chambers 12 and 13 areconnected with the upper regions of smaller chambers 1d and 15 by meansof conduits 22 and 23 controlled by means of remotely controlled valves24 and 25 respectively. The smaller chambers are separated from accessshaft 26 by walls 27 and 28. The large chambers 12 `and 13 can be lledfrom pipeline connections 30 and Si through vertical filler pipes 32 and33. The filling of the large chambers from the pipe line connections 30Vand 31 can be controlled by means of valves 34 and 35, respectively.

In accordance with my invention the underground storage system can beoperated cyclically. Assuming that small chamber i4 has been filled orpartially filled with liquid from large chamber 12, liquid from smallchamber 14 is forced to the surface through conduit 36 by means of`vapor withdrawn from small chamber 15 via lines 40, 4l, 42 and 43through valves 39, 44, 45 and 46 which is pumped by compressor 56 to theupper region of smaller chamber 14 by means of lines 51 and 52 throughvalve 53. During this operation valves 21 and 24 will be closed andvalves 20 and 25 open during which time liquid in larger chamber 13 maybe allowed to flow through conduit 16 and valve 20 into smaller chamber15. Normally this filling will be effected by gravity flow, until thelevel of liquid in small chamber 15 is equal to the level in largechamber 13. As an alternative method of operating the filling step,valve 25 may be kept closed andthe level of liquid in small chamber 15allowed to rise above the level in large chamber 13 by virtue of thesuction exerted upon the surface of liquid in smaller chamber 15.However, when operating in such a manner extra Work is required ofcompressor Sli once the level of liquid in the small chamber is equal tothat in the large chamber.

By `the system of conduits shown in Figure `1 it is possible to withdrawvapor from larger chamber 13 exclusively, if for some reason it is notdesired to till the 3 small chamber 15. In such a case valves 20 and 25would be closed and vapor would be withdrawn through lines 33, 54, 55,41, 42 and 43 through valves 56, 57, 58, 60, 44, 45 and 46.

After small chamber has been filled in either of the manners hereinabovedescribed and small chamber 14 emptied, liquid therein is forced to thesurface through conduit 61 by means of vapor withdrawn from smallerchamber 14 via lines 52, 62, 42 and 63 through valves 3S, 64, 65 and 66pumped by means of compressor 70 down to the upper region of smallerchamber 15 via lines 71, 55 and 40 through valves 6i) and 39. Duringthis operation valves and 25 will be closed and 21 and 24 will be openthus permitting liquid from larger chamber 12 to ilow into smallerchamber 14 to till or partially till same in the manner hereinbeforedescribed. Also, it is possible when emptying small chamber 15 towithdraw vapor eX- clusively from larger chamber 12 via lines 32, 72,51, 62, 42 and 63 through valves 73, 74, 53, 64, 65 and 66.

Referring to Figure 2 ofthe drawing in detail, illustrated is anotherembodiment of my invention wherein a modication of the conduit system isemployed and only a single compressor utilized. ln operating theunderground system in accordance with this modification of my invention,it is possible while emptying smaller chambers 110 or 111 through lines112 and 113 respectively, to withdraw vapor from any ofthe otherchambers, large or small, in the storage system. Thus, assuming smallchamber 110 to be filled or partially filled with liquid from largerchamber 114, vapor with which to pressure small chamber 110 can bewithdrawn from larger chamber 114 via lines 115, 117, 118, 120, 121, 122through valves 123, 124, 125, 126 and 127, and pumped by compressor 139,to small chamber 110 Via lines 131, 132, 133 and 134 through valves 135and 136. During said operation remotely controlled valves 140 and 141will be closed. Also, during said operation any activity desired in theother portion of the system, viz, `small chambers 111 and large chamber142, such as lling of smaller chamber 111 by the opening of remotelycontrolled valve 143 and 144, or the lilling of larger chamber 142 frompipe line connections 145 through line 146 and tiller pipe 147 throughvalve 148, or even repairs to said chambers, can be effected.

When emptying smaller chamber 110 it is also possible to withdraw vaporin a manner analogous to that described in the description of theoperation of Figure l, namely, withdrawing vapor from smaller chamber111 via lines 150, 151, 121 and 122 through valves 152 and 127, duringwhich time remotely controlled valves 143 and 144 will be open thuseffecting a filling of smaller chamber 111 from liquid in larger chamber142. Alternatively, vapor for pressuring smaller' chamber 110 can lbewithdrawn from larger chamber 142 exclusively via lines 147, 118, 126and 122 through valves 153, 126 and 127.

When emptying liquid from smaller chamber 111, it is again possible towithdraw pressuring vapor from any of the other chambers in the systemin a manner analogous to that employed when emptying smaller chamber110. Thus, pressuring vapor may be withdrawn from large chamber 142 vialines 147, 117, 155, 156, 132, 157, 158, 161i and 122 through valves153, 125, 124, 161 and 162. 'The vapor is pumped by means of compressor13) through lines 163, 164, 165, 121, 151 and 156 through valves 166 and152. Valves 143 and 144 will be closed during such operation.

Alternatively vapor for pressuring small chamber 111 may bc withdrawnfrom small chamber 110 via lines 134, 133, 132, 157, 158, 166 and 122through valves 136 and 162 and pumped by compressor' 130 through lines131, 163, 164, 165, 121, 151, and 159 through valves 166 and 152. Duringsuch operation valves 140 and 141 can be either opened or closed. 1fthey are opened, tilling of smaller chamber 110 from liquid in largerchamber 114 can bc effected. lt is also possible, to fill larger chamber4 114 from pipe line connection 170 through'lines 1'15 and valve 171,

Alternatively vapor for pressuring smaller chamber 111 may be withdrawnexclusively from larger chamber 114 via lines 115, 155, 156, 132, 157,158, 160 and 122 through valves 123, 161 and 162, and pumped bycompressor 130 to smaller chamber 111 via lines131, 163, 164, 165, 121,151 and 150 through valves 166 and 152.

Referring now in detail to Figure 3 of the drawing illustrated isanother modiiication of my invention wherein two small chambers 210 and211 are used for emptying `a plurality of larger chambers 212, 213, 214,and 215. The bottom region of each of the larger chambers connects withthe bottom region of each of the smaller chambers by means of manifold216 and conduits 220, 221, 222 and 223, the llow through which iscontrollable by means of valves 224, 225, 226 and 227. Liquid from anyof the chambers may be directed into either of the smaller chambers 210or 211 depending upon whether valve 230 or 231 is opened. A ventingconduit system is illustrated connecting the upper regions of each ofthe larger chambers with the upper region of each of the smallerchambers by means of manifold 232 and conduits 233, 234, 235 vand 236the ow through which is controlled by means of valves 240, 241, 242 and243. Liquid from either of the smaller chambers 210 or 211 passes to thesurface through manifold 244 and line 245 depending upon whether valve246 or 247 is opened. Manifold 250 connecting the upper regions ofsmaller chambers 210 and 211 connects with the surface by means of line251 which in turn connects with the suction end of compressor 252 bymeans of lines 253 and 254. Vapor can be withdrawn from the upper regionof either chamber 210 or 211 by opening either valve 255 or 256. Vaporis pumped by means of compressor 252 to the upper region of either ofthe smaller chambers 210 or 211 via lines 260, 261, 262 and manifold263. Pressuring vapor is passed to either smaller chamber 210 or l211depending upon whether valve 264 or 265 is open.

Each of the larger chambers connect with the surface by means of llerpipe 270, 271, 272 and 273 controlled by valves 274, 275, 276 and 277respectively. These filler pipes are connected to a common manifold 280which can connect to pipe line connections 281 and 282 controllable l byvalves 283 and 284 and which connects with the suction end of compressor252 by means of lines 285, 253, and

254 and controlled byvvalve 286. v

The methods of operating the underground storage system illustrated inthis ligure are extremely variable. lt is possible by the arrangementshown't'o ll eitherof the smaller underground chambers from any of thelarger chambers. When emptying either of the smaller charn bers vaporcan be withdrawn from anyother chamber in the entire system, large orsmall. Thus, according to one method of operation, assuming smallerchamber 210 has been tlled with liquid from any of the larger chambers,liquid in said small chamber 210 is forced to the surface throughmanifold 244 and line 245 through valve 246 by means of vapor withdrawnfrom smaller chamber 211 via manifold 250, lines 251, 253 and 254through Valve 256 by compressor 252 and passed to chamber 210 via lines260, 261, 262, manifold 263 and through open valve 264. During suchoperation small chamber 211 may be lled from any of the larger chambers212, 213, 214 0r 215. The appropriate valves and vents can be openedaccord'- ingly. In operating in this manner it is possible to ll any ofthe large caverns from the pipe line connections'. Iln such case valve286 would be closed. It is also possible by this arrangement to storeliqueable gases of different compositions in a single undergroundstorage system.

By the arrangement of smaller and larger caverns shown in this gure ofthe drawing, a saving inthe num ber of smaller caverns necessary iselected and greater flexibility of operation is obtained. Further, allvalves which need be controlled are more readily accessible` for avancermaintenance since they can "be placed at the bottom of accessshaft"2l90. p

`In the ldescription of the figures of the drawing it has been pointedout that it is possible vto 'till a larger cavern from the pipe line atVthe saine tir'ne that liquid is being withdrawn from storage. At Vtimesthe pipeline delivers LPG `faster than it can vbe used and `there is anet gain in storage, `while at other times 'little LPG is available fromthe `pipe line while 'thereis a llarge demand for the fuel, this demandbeing satisfied by reducing storage. The systems which are shown in thedrawings will operate satisfactorily lunder varying 'conditions sincethe two operations, `filling and emptying, are `independent and can becarried out simultaneously at different rates.

The size` of thesmafller cavern len'tployed from which storage isreduced will vary depending upon many factors, such as, the size of abatchneeded during a single filling operation at the surface, the mostefficient amount of gas that can be compressed in order to Ystart theflow of liquid to the surface, and the amount of surrounding earth whichwill 'reduce to `economic limits -the amount o'f heat loss in 'thepressuring operation. Comparisons between 'the size of the largerchambers `and the smaller chambers would not 'be helpful in view of theforegoing considerations and since the 'size of large 'undergroundstorage Caverns are almost without limit. Most of the advantages of myinvention are present merely if the chamber which is pressured issmaller -than the main storage cavern.

While my invention has been described in terms of its preferredembodiments those skilled lin the art will appreciate that manymodifications can be made without departing from the spirit and scope ofmy invention as defined herein.

I claim:

l. In an underground storage system, in combination, a large undergroundstorage cavern; a smaller underground dispensing cavern; valved conduitmeans connecting the upper regions of both cavems; valved conduit meansconnecting the lower regions of both Caverns; conduit means connectingthe lower portion of said dispensing cavern with the surface; a fillerpipe connecting the upper portion of said large cavern to the surface;and compressor means communicating with the upper region of said smallerCavern and with a source of pressurizing gas to supply compressed gasinto the space above the liquid level of the smaller cavern, thecapacity of said compressor means being minimized due to the small heatloss through the walls of the dispensing cavern.

2. In an underground storage system, in combination, a plurality oflarge underground Caverns; an equal number of small underground Cavernspaired with each of said larger Caverns; valved conduit means connectingthe upper region of each of said larger and smaller Caverns; valvedconduit means connecting the lower region of each of said larger andsmaller Caverns; conduit means connecting with the lower region of eachof said smaller Caverns and extending to the surface; liller pipe meansconnecting with the upper region of each of said larger Caverns andextending to the surface; and compressor means connected to pressure anyof the smaller Caverns while withdrawing vapor from any of the otherCaverns in the underground storage system.

3. In an underground storage system, in combination, an undergroundstorage Cavern; means within said underground storage Cavern dividingsame into a larger section and a smaller section; valved Conduit meanscontrollable from the surface connecting the upper regions of saidlarger and smaller sections; valved conduit means con trollable from thesurface connecting the lower regions of said larger and smallersections; Conduit means Connecting with the lower region of said smallersection and extending to the surface; liller pipe means connecting withthe upper region of said larger section and extending to the surface;and compressor means connected to pressure the smaller `section of saidcavern `'while withdrawing Avapor 'lower region of each ofsaid^sma1lersections and extending to the surface; filler' pipe meansconnecting with theupprer region of each of said larger sections andextending to the surface; va valved conduit system interconnecting theupper regions of all of the sections in the underground `storage system;and compressor means connectedlin 'said conduit system 'to pressure any`of the smaller sections of the underground storage Cavernswhilewithdrawing vvapor from any ofthe other sections' inthe'undergroundstora'g'e system.

5. In an underground storage system, in combination, two undergroundstorage Caverns; `means dividing each of said Caverns into "a largersectionand a 'smaller section; valved conduit means controllable Vfromthe surface connecting the upper regions 'of each of saidlarger andsmaller sections; similar means connecting the lower regions of each ofsaid larger and smaller sections; conduit means connecting with thelower region of each of said smaller sections and Iextending 'to thesurface; filler pipe means connecting with the upper region of each ofsaid larger sections and extending to the surface; a valved conduitsystem interconnecting the upper regions of all of said sections in theunderground storage system and including said filler pipe means; onecompressor connected in said conduit system to pressure one of saidsmaller sections while withdrawing vapor from the other smaller sectionor the larger section adjacent thereto; and] a second cornpressorconnected in said conduit system to pressure the other smaller sectionwhile withdrawing vapor from said rst-mentioned smaller section or thelarger section adjacent thereto.

6. In an underground storage system, in combination, a plurality oflarger underground storage Caverns; at least two Caverns smaller thanany of the larger Caverns; valved conduit means connecting the bottomregion of each of said larger Caverns with each of said smaller Caverns;valved conduit means connecting the upper region of each of said largerCaverns with the upper region of each of said smaller Caverns; fillerpipe means connecting the upper region of each of said larger Cavernswith the surface; a valved conduit system interconnecting the upperregions of all of the Caverns in the underground storage system; andcompressor means connected in said conduit system to pressure any of the:smaller Caverns while withdrawing vapor from any of the remainingCaverns in the underground storage system.

7. In a process for removing volatile liquid from storage in a largeunderground cavern by displacement with gas under pressure, said gasbeing in heat exchange relation to the surrounding earth and at atemperature above the temperature of the surrounding earth and theaverage temperature of sai-d volatile liquid in storage so that if saidgas is applied under pressure to said large under ground cavern, largeheat losses would result from said gas to the surrounding earth and tosaid volatile liquid in storage thereby tending to lower the pressure ofsaid gas and hence its displacement eiliciency, an improved method ofremoving said volatile liquid whereby said heat losses from said gas areconsiderably reduced thus conserving the energy in said gas, whichcomprises transferring volatile liquid from said large undergroundcavern to an underground dispensing chamber communicating therewith andhaving substantially less volume and surface area and hence offeringless opportunity for heat transfer to the surrounding earth than saidlarge underground cavern and communicating from the lower portionassess? of said dispensing chamber to the surface of the earth, 'closingcommunication with said underground cavern,

and pressurizing said underground dispensing chamber with said gasthereby displacing volatile liquid from vsaid ydispensing chamber to thesurface of the earth.

8. In a process for removing liquefied gases from storage in anunderground cavern by displacement with pressurized gas, the improvedmethod of reducing heat losses from said pressurized gas to thesurrounding earth which comprises passing said liquefied gases from saidunderground cavern to a first underground dispensing zone having lesssurface area and volume than said underground cavern, withdrawing vaporsfrom a second underground dispensing zone, allowing liquefied gases toow from an underground storage zone to said second undergrounddispensing zone while said vapors are withdrawn therefrom, compressingsaid vapors, and passing said vapors thus compressed to said firstunderground dispensing zone thereby displacing said liquefied gasestherein to the surface of the earth.

9. in a process for removing liqueed gases from storage in anunderground cavern by displacement with pressurized gas, the improvedmethod of reducing heat losses from said pressurized gas to thesurrounding earth which comprises passing ysaid liquefied gases fromsaid underground cavern to a first underground dispensing zone havingless surface area and volume than said underground cavern, withdrawingvapors `from a second underground dispensing zone, allowing liqueedgases to flow from an underground storage zone to said secondunderground dispensing zone while said vapors are withdrawn therefrom,said second underground dispensing zone having less surface area andvolume than said undergroundy storage zone, accumulating liquefied gasesin said second underground dispensing zone, compressing said vapors,passing said vapors thus compressed to said tirst underground dispensingzone thereby displacing said liquefied gases therein to the surface ofthe earth, thereafter passing liquefied gas from said underground cavernto said first underground dispensing zone again, withdrawing gases fromsaid first underground dispensing zone, compressing said gases, andpassing said gases thus compressed to said second underground dispensingzone thereby displacing liquefed gases therein to the surface of theearth.

References Cited in the file of this patent UNITED STATES PATENTS2,075,678 Von Langen Mar. 30, 1937 2,296,598 Cook Sept. 22, 19422,387,894 Fannin Oct. 30, 1945 2,433,896 Gay Jan. 6, 1948 2,670,605 VanZandt et al. Mar. 2, 1954 FOREIGN PATENTS 435,080 Canada June 4, 1946

